Apparatus for separating substances of different dielectric capacities



'H. M. sunom AND w. AND E. G. STE ELIE. APPARATUS FOR SEPARATING SUBSTANCES OF. DIFFERENT DIELECTRIC CAPACI T|ES..

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APPLICATLQN FILED SEPT- 24, 1904-- I trostatic field.

lished whenever a series of metallic points UNITED STATES PATENT OFF ICE.

HENRY M. SUTTON, WALTER L. STEELE, AND EDWIN G. STEELE, OF DALLAS, TEXAS.

APPARATUS FOR SEPARATIN G SUBSTANCES OF DIFFERENT DIELECTRIC CAPACITIES.

Specification of Letters Patent.

Patented Aug. 2, 1921.

Application filed September 24, 1904. Serial No. 225,852.

T 0 (ZZZ whom it man concern Be it known that we, HENRY M. SUTTON. WALTER L. STEELE, and EDWIN G. STEELE,

citizens of the United States, residing at Dallas, in the county of Dallas, State of Texas, have invented certain new and useful Improvements in Apparatus for Separating Substances of Different Dielectric Capacities, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to an apparatus for separating substances of different dielectriccapacities, and particularly to a machine for producing in the material conveyed therethrough a dielectric hysteretic impedance.

This invention has for an object to provide means for conveying the material to be separatedinto its component particles into the field of means for producing in the material dielectric hysteretic impedance in connection with means for collecting the separated particles of the material in accordance with the difference in time that said particles maintain their polarity due to the impedance generated therein. This dielectric hysteretic impedance may be produced in accordance with the process set forth in our Patent No. 813,063, dated February 20, 1906, or by any other proper means, such, for instance, as feeding the material to an extremely unbalanced elec- Such a condition is estabor a sharp edge is connected to a source of static or high tension electricity, and the latter is allowed to escape across an intervening space to a surface of conducting material which is grounded to the earth or connected to the opposite pole of the electrical source of energy to that connected to the points or sharp edge. This produces avery highly concentrated electrostatic field, and when a commingled mass of particles is fed into such a field, the particles are unable to attain a permanent equilibrium as the conducting surface over which they are conveyed has absolutely no power of repulsion and the points or sharp edge has absolutely no power of attraction. The fact that the particles adhere to such a conducting surface is due to the residual charge impart} held in the ed to these particles by the electrostatic stress upon them from the points or the edge to the grounded surface, and only occurs in a line approximately opposite the points. In order that this operation may be fully understood reference is made to the well known fact that an insulated conducting surface inorder to maintain a charge of static electricity that has been imparted to it, must be free from all sharp edges or points, as a pointed substance either attached to a charged conductor or proximity of it would rapidly discharge the electricity therefrom. Therefore, if a sharp point be attached to a charged surface of a static machine and a plate of conducting material which is or may be grounded to the earth is placed a short distance from said point, there will be a rush of electricity or constant flow from the point to the plate in contradistinction to a disruptive discharge. This form of charge is commonly known. as convective. It is impossible under these conditions to charge the point with its full potential as. t

it is discharged as fast as the current is being delivered to it from the machine. In fact, the point is receding from a full poten tial instead of approaching it, and by this means an unbalanced electrostatic field is established. N ow, if a particle of any substance be mova-bly suspended between the plate and the point of the conductor it Wlll be attracted to the plate and adhere indefinitely to it as long as this condition due to the convective discharge is maintained as there will be no equilibrium established 1n which the substance charged can reach a potential that will enable it to be attracted to the point or be repelled from the grounded surface even if such a surface be connected to the opposite pole of the static machine from that of the point. From this illustration it will be seen that dielectric hysteretic impedance is generated in any substance to a greater or less degree when that substance is subjected to an unusual electrostatic stress or strain.- In the instance just mentioned the electricity escaping from the surface to which a sharp point or edge is attached escapes by convection and acts directly upon the material brought near it and not inductively and, passes gradually and silently to particles to be charged, acting as if the said particles were surface, that is to say, at both sides of the charged surface. This dielectric hysteretic impedance may be produced by contact wlth a single surface subjected to an alternating,

. pulsating or varied static charge, as fully set forth in the patent before mentioned, or by means of a continuous current where the material is brought adjacent to a charging point and is charged with electricity of the same sign as that escaping from the point, thus establishing in the material opposite electrical conditions upon its surfaces if a grounded conducting surface be disposed adjacent to the material.

-of the invention will behereinafter set forth and the novel features thereof defined by the appended claims.

In the drawing: Figure .1 is aperspective with parts in section illustrating the electrical connections;

Fig. 2 paratus;

3 is a side elevation thereof Fig. 4 is a rear elevation;

is a vertical cross section of the ap- Fig. 5 is a detail perspective of the means for adjusting the division plate;

Fig. 6 is a similar view of the means adjusting the electrified points;

Fig. 7 is a side elevation with a part broken away of the slotted interrupter plates; W v

Fig. 8 is anedge view of these plates and the1 means for relatively adjusting the same, an 7 Fig. 9 is a detail perspective showing circuit connections to andfrom the interrupter.

Like letters refer to like parts in the sevfor ' eral figures of the drawings.

The letter A designates a hopper which is mounted in any suitable manner, for instance, upon a frame A constructed in accordance with the requirements of the machine. a

The material to be separated is fed from I the lower portion of the hopperby means of a spout A? into a. shaker pan A which'is pivotally'supported by hangers A and con-.

brought in contact with the adjacent and opposite electrically chargednected to an eccentric D upon the shaft D by means of the strap D and thus by its reciprocatory motion feeds the material upon a spreader'tray F. This tray is preferably formed of metal and has its bottom fluted or ribbed, as shown at F in Fig. 1, which ribs extend nearly to the delivery edge of the tray, such edge, however, being left perfectly smooth, as indicated at F. The object of this is to prevent bunching of the material tray, as the feed from'the shaker pan is somewhat narrower than the tray, and into the flutes or ribs which prevent it from reaching the edges of the tray during the lateral movement thereof. This -.tray is given a lateral or side shake by means of the eccentric F mounted on the shaft F and connected to the tray by means of a strap F said tray being mounted 'to reciprocate upon the rods F by means of the bearings F upon the bottom of the tray. The tray is also given a downwardv inclination toward the conveying surface which is illustrated in the present instance as a metallic roller Ur. When the material is fed to this tray from the shaker pan the lateral movement of the tray causes the material to feed down the grooves to the smooth portion of the tray Where its motion causes it to spread out into a thin layer and the material is thus prevented from reaching and collecting in the corners of the tray so thata delivery to the metallic roller in a thin uniform layer is insured.

This roller G may be constructed entirely of metal or of some good conducting material, and both it and the spreader tray F are electrically connected to the ground by means of the line C, so that they are incapable of sustaining a charge of electricity at the corners or sides of the which may be imparted to them, as such charge would be immediately grounded.

This connection may be grounded by any desired means, for instance, the wire C" from the tray andthe wiper C bearing upon the shaft G of the roller.

Adj acent" to the roller G, as shown in Figs. 1 and 2, are one or more thin metallic rods H each provided with a series of'sharp metallic points H (Fig. 6) directed toward the surface of the roller or their equivalent of a sharpened edge H which comprise the Y 1 charging means. This means is connected to i one pole of an electrostatic generator, as indicated at C or to any other source that is capable of applying static electricity, and v the current is conducted therefrom to the charging means by means to be hereinafter described. The material to be treated is fed from the tray upon the roller as just described, and passing convectively under the points or chargin convectively to the grounded roller, 0. Inameans from which the .'currents of electricity are constantly passing in the direction of said plate,

- and provided with a driving terial dielectric impedance is set up in certain particles of the mass, while others remain unaffected. These unaffected particles drop upon the division plate I simply by the-motion of the roller as it revolves they being neither repelled by the cylinder nor attractedby the charging means and pass from this plate into a suitable chute I" where they are conducted to a receptacle. The particles which have small dielectric impedance are drawn closer toward the face of the roller and thus pass behind the division plate and drop into the chute I while those which have a very great impedance would remain attached to the cylinder and are thus carried past the adjustable partition I so that they may be deposited in the chute I and this depositing of the material adhering to the roller may be accomplished by releasing the material therefrom by any desired means, preferably by an electrically charged rod I-I disposed at the back of the cylinder and connected by means of a line C with a source of static electricity whose polarity is opposite to that supplied to the charging means, for instance, to the opposite side of the static generator C as shown in Fig. 1. To effect a continuous or constant charge on the rod H and regulate the same, a' regulator Q is shown inserted in line C, and provided with the pointed discharge terminal Q mounted in its post Q relative to the rounded terminal Q opposite thereto. The effect of this is to depolarize the particles when they come within the influence of the rod which extends longitudinally of the roller, and the particles are thus released to fall into the compartment I The parts heretofore described may be driven by any desired means, for instance, the shaft J mounted upon the framework A pulley J. Disposed upon this same shaft is a cone pulley J 2 connected with a similar oppositely disposed pulley J 3 carried by the parrallel countershaft J and driven by means of the belt J Intermediate of the cone pulleys a belt shifter J of any ordinary construction may be disposed and is adapted to shift the belt J along the cone pulleys for the purpose of imparting to the metallic roller any desired speed. The power is transmitted from the shaft J to the roller bymeans of the pulley J upon the shaft J and a belt J extending therefrom to a' driving pulley J 9 upon the roller.

For the purpose of driving the shaft F which controls the vibration of the tray, a driving pulley J is disposed upon the-op-' posite end of the shaft J from the pulley J and is provided with a twisted'belt J extending to a pulley J of the shaft F.

The shaft J is also provided with a drlving pulley K from which m0- carried upon the end tion is communicated by the belt K to a pulley K upon the driving shaft D for the shaker pan A". In order that the division plate I disposed adjacent to the roller shall not retain the charge of electricity it is preferably formed of proper conducting material and grounded to the earth by means of a line C extending therefrom, as shown in Fig. 1. This plate is also mounted for adjustment relative to the roller by means of a bracket I secured to a fixed support and provided at its freeend with an adjustable arm I adapted to be held in adjustment by a screw I while the plate I is rotatably mounted at the free end of this arm by means of a pintle I extending through a bearing carried by the arm and held therein by a set screw I, so that the plate may be adjusted and held to any desired position, as shown in Fig. 5. This plate I forms a shield for determining the extent of the surface of the roller G to be exposed to the charge, and the feed tray F also effects a similar function.

In Fig. 6 a similar construction is illustrated for adjustably mounting the charging means H to control the current supplied to the-separating electrode and comprises a bracket H secured to a fixed part, and an adjustable arm H held by the bracket by means of a screw H, while the charging device is mounted in a bearing H at the upper end of this arm and held therein by means of a set screw H lVhen it is desired to interrupt or pulsa-te 100 the charge or change the polarity of the currents for establishing the dielectric separation, it may be accomplished by any desired form of interrupter, although we have illustrated in Figs. 7 and 8 a preferred con- 105 struction thereof adapted for either purpose in which the plates L and L are each provided with a series of slots L and L respectively. The disk L is fixed to a driving shaft L adapted to be rotated in any de- 110 tired manner, by means of a set screw L while the disk L is provided with a collar.

L extending therefrom and formed in two parts separated diagonally, as indicated at U. The portion of the collar L carried by 115 the disk L is loosely mounted upon the I shaft L to rotate thereon but held against longitudinal movement, while the separated portion L of the collar is free to reciprocate upon the shaft, but prevented from 120 turning thereon by means of a key or feather L". The members L and L of the collar are connected together by means of a suitable spring L coiled around the same. For

carrying a threaded nut M which is pro- 1.80

vided with a forked portion M engaging the section L of the collar so as to shift the same upon its driving shaft. If the hand wheel be operated to shift the movable section of the collar toward the support it will cause one disk to advance ahead of the other in its rotation. This movement of the disk is effected by a relative movement of the diagonally disposed adjacent ends of the collar members L and L When the latter member is moved upon the shaft it 'continues its rotation but separates from the adjacentend of the collar member L and the encircling spring connecting the two members exerts a retarding tension upon the member L thus causing it to partially rotate and bringing the apex of the diagonally disposed end thereof at a different point upon the adjacent end of the member L which varies the relative position of the disk L to that of the disk L which is driven from the same shaft but always, in a fixed relation to the collar mem'ber L The more the movable collar section is shifted away from the disk L the farther one disk will be moved ahead of the other, and, consequently, the slots or openings through the two disks from one electric terminal to the other will be diminished in length until practically the limit is reached, as indicated in Fig. 7, where only a small opening is provided. It will be obvious that an adjustment of the hand wheel to the opposite extreme of movement brings the slots in the two disks into alinement,

and thus provides the maximum openingbetween the electric terminals. These terminals C are connected to one side of a static machine by means of a line C, which, if desired, may be provided with a switch C and the opposite terminal C is connected to the charging means H by means of a line C extending therefrom. Under those conditions of work where it is desirable to omit the use of the interrupter or pole changer just described, the current may be taken from the static machine directly to the charging means by the line C which is also provided with a switch C so as to be cut out when the interrupter or pole changer is used. This interrupter when arranged as shown is Fig. 1, interrupts or pulsates the charge, and when it is desired to alternate the polarity thereof, the same device is arranged as shown in Fig. 9, wherein the terminals are duplicated as at O and O and connected to the opposite poles of a static machine, while upon the other side of the disk the terminals 0 are provided to alternately receive current through the slots therein and are connected in circuit with the line wire C extending to the charging feeders, as shown in Fig. 1. "This interrupter provides means for maintaining an effective charge on the charging electrode during a fractionof the wave of the charge and for rendering said electrode inactive at recurring intervals and regulating the duration of said intervals.

It is desirable in the successful operation of the apparatus that the roller or other conducting means for the material should be grounded to the earth so that substantially zero potential, to render the roller inactive electrically, may always be maintained and the roller has then absolutely no repulsive power. The particles having been strongly polarized in the manner described, remain clinging to this surface by virtue of their residual charges and remain in contact as long as these charges last. As there is a difference in the period of time the particles maintain their polarity it is thus possible to make a large number of separations upon one roller, for, as the materials lose their polarity they can be dropped into different compartments during the rotation of the roller which cannot be successfully accomplished when the particles are fed to any charged surface.

We have specifically described herein means for producing dielectric hysteretic impedance in the material to be treated, but the invention contemplates the use of any means for this purpose and is not specifically confined to those herein disclosed. This impedance is generated in any substance when it is exposed to an unequal static strain whether that strain be produced in the manner hereinbefore described or by an alternating, pulsating'or varied static charge, as described in our patent before mentioned.

It will be observed that heretofore in this art separation has been effected either by charging the material with electricity or feeding the same upon an electrically charged surface, relying on the difference in time when a conducting material will lose its charge as compared to a nonconducting material when both are brought into contact with a surface charged at a difierent potential. In this case the material to be sepa-' rated never rests upon a charged surface but upon a surface which is incapable of sustaining a charge of electricity and at no time during the operation is the mass of particles allowed to take a prior charge, as such an effect would be liable to interfere with the residual polarity impressed upon the particles by the discharge of electricity from the points. By connecting the supporting or conducting surface for the material with the earth it has no power of repulsion and remains always at the electrostatic potential of the earth which is substantially zero or inactive potential.

The term dielectric hysteretic impedance is herein used as defining a lag of charge in particles of matter under the influence of alternating or irregular stress produced from any desired source of energy. This lag of charge results in maintainingv a difference of potential in or on the particles whereby materials of either a conductive or nonconductive character may be treated and separation effected between materials of different degrees of conductivity as well as between materials of relatively .difi'erent nonconductive properties. In this process the production of the lag of charge or dielectric hysteretic impedance by which separation is accomplished is by convective discharges and the interrupter acts merely as a means to govern the development of'this lag and not its production.

Inasmuch as the difference in the dielectric capacity of particles is altered or governed by their conductivity or, in other words, the amount of electricity which they allow to pass across them by conduction and also by the amount of electrical influence they allow to pass through them by induction the process acts to separateparticles of different degree of conductivity as well as of inductivity. A synonymous term sometimes used in place of inductivity is that of specific inductive capacity.

It has been found that dielectric hysteretic impedance is greatly increased if the particles or mass of material are fed to the roller or subjected to the electric charge while in a heated condition or 'at approximately a temperature of 120 F. Any form of heater may be used to thus heat the material at any proper stage of its operation which constitutes a material improvement in this art, but there is illustrated in the present case an electric heater N in Fig. 2, which may be connected by lines N and N with any suitable source of power for the purpose of heating the tray F over which the thin layer of material passes in its travel to the roller.

The feeding of the particles to the separating electrode while heated causes a rapid dissipation of the residual charge upon both the particles and the electrode as the latter is grounded, and this rapid dissipation renders the particles highly susceptible to the convectively delivered charge, and at the point of contact of the particles with the electrode produces a more intense electrostatic stress between some of the particles and the electrode than can otherwise be secured, and therefore causes a greater diiference of potential between the particles and the electrode. The metallic or conducting particles when heated are rendered more inert to the convective charge than ordinarily and'therefore less liable to be affected by such a charge as it is essential that they remain practically inert during the charging of the dielectrics. The feeding of the heated particles heats the separating electrode and therefore facilitates the more rapid discharge thereof so that it may be quickly reduced to an inactive potential when the charge is interrupted. This charge is localized upon some of the particles, that is, the opposite surfaces thereof are inductively charged with opposite potential, and one side of such a particle is of a different potential and polarity from the bound charge upon said electrode in order to cause a temporary adherence of some of theflparticles thereto. The charges are thus delivered to the grounded electrode without inductively charging the latter. use a phase or portion of the full charge from the generator when said charge is applied to separating particles that differ but slightly in their lag of charge or dielectric capacity as if the charge continues for the full phase or period the particles that differ but slightly in such capacity would adhere to the electrode with the other particles of the mass, and therefore but a portion, such as the peak or highest potential of each phase or charge, is used and not the full duration -thereof. The term phase is herein used asrelating to the duration of thechar e and not in a specific sense as in some of t e electrical arts.

It will be obvious that changes may be made in the details of construction and configuration of the several parts of the apparatus without departing from the spirit of the invention as defined in the appended claims.

Having described our invention and set forth its merits, what we claim and desire to secure by Letters Patent is 1. In a dielectric separator, the combination with means for producing dielectric hystereti'c impedance in the material to be separated, of a relatively movable nonrepellent electro-static separating means, and means for separately collecting the separated material.

2. In a dielectric separator, the combination with means for producing dielectric hysteretic impedance in the material to be separated, of a relatively movable nonrepellent separating means, means for heating the material and feeding it to the separating means while heated, and means for separately collecting the separated material.

3. In a dielectric separator, means for electrically charging material to be separated therein, means for heating the material and feeding it into the influence of the electrical charging means while heated, and means for separately collecting the separated material.

4. In a dielectric separator, an electrically grounded roller, means opposite said roller for producing dielectric hysteretic impedance of material passing thereover, means for collecting said material beneath said roller, means for electrically releasing material from said roller, a vibrated tray for discharging material upon said-roller, a di- It is advantageous to vision plate disposed at the front of said roller, means for electrically grounding said division plate, and means for heating said tray.

5. In a dielectric separator, an electrically grounded roller,'means opposite said roller for producing dielectric hysteretic imped-- face, a source of electrical energy, a line leading therefrom to said charging device, an interrupter interposed in said line and having adjustable means for varying the charging periods, and means for separately collecting the separated particles.

7. The combination with a grounded separating device, of means for feeding comminuted material adapted to pass the material through the path of convection at an angle thereto, a charging device adapted to convectively deliver charges to the grounded separator, a series of compartments beneath said separating device, a division plate adjustably mounted adjacent to one face of said separating device and discharging into one of said compartments, and means for separately collecting the separated particles.

8. The combination with a grounded separating device, of a charging device adapted to convectively deliver charges to the grounded separator across the path of travel of the material, a series of compartments beneath said separating device, 'a division plate adjustably mounted adjacent to one face of said separating device and discharging into one of said compartments, a pivoted partition disposed beneath said separating device and adjacent to one surface. thereof, and means for removing the electrically adhering material from said separating device. 9. The combination with a grounded separating device, of a charging device adapted to deliver charges to the grounded separator, a series of compartments beneath said separating device, a division plate adjustably mounted adjacent to one face of said separating device and discharging into one of said compartments, a pivoted partition disposed beneath said separating device and adjacent to one surface thereof, means for removing the adhering material from said separating device, and means for adjusting said charging device relative to the surface of said separating device.

10. The combination with a separating device, of an electrical charging device adjacent thereto, a feeding tray adjacent to said separatin device and provided with a series of parallel ribs extending longitudinally thereof, means for agitating said tray laterally, a hopper, a pan beneath said hopper and discharging into said tray, means for agitating said pan toward and from said tray, and an electrical heatingdevice supported at the under face of said tray.

11. The combination with means for electrically charging material, of a separating device, a feed tray therefor, and a heating device carried by said tray to heat the material preliminarily to receiving its electrical charge.

12. The combination with means for electrically charging material, of a separating device, a feed tray disposed to discharge upon said device, and an electrical heating device disposed at the under face of said tray.

13. In an apparatus for separating the particles of a mass, means for heating said particles, means for electrically charging said particles while heated, and means for separately collecting the separated particles.

14. In an apparatus for separating'the particles of a mass, means for heating said particles, means for subjecting said particles to a varied electrical charge while heated for developing therein a lag of said. charge, and means for separately collecting the separated particles.

15. The combination with an electrically grounded separating device, of a charging device adapted to deliver an electrostatic charge to particles of materials without inductively charging the separating device, means for' feeding comminuted material thereto, an interrupter in circuit with said charging device, and means for separately collecting the separated particles.

16. The combination with an electrically grounded separating device, of a charging device adapted to deliver an electrostatic charge to particles of material without inductively charging the separating device,

means for feeding comminuted material thereto, an interrupter 1n clrcuit with sald charging devlce, means for delivering to said charging device an interrupted static charge, and means for separately collecting the separated particles.

17. The combination with an electrically grounded separating device, of means for producing adjacent thereto a regulated static charge in dielectric particles to be separated varied in its duration, and an electrically grounded feed tray adjacent to said separating device.

18. The combination with an electrically grounded separating device, of means for producing adjacent thereto a regulated static charge in the particles to be separated varied in its phase, an electrically grounded feed tray adjacent to said separating device, a. releasing device adjacent to the surface of said separating device and statically charged at the opposite potential to the primary charging device, and a conducting division plate adjacent to said separating device and electrically grounded.

19. In an apparatus for separating the particles of. a mass, means for feeding comminuted material, means for convectively delivering charges across the path of material, means for adjusting the device for the desired duration of charging periods at its point of application to develop in some of the particles a lag of electrical charge from the point of contact of a particle with an adjacent electrode, and means for separately collecting the separated particles.

20. In an apparatus for separating the particles of a mass, means for feeding comminuted material, means for convectively delivering charges across the path of material, means for adjusting the device for the desired duration of charging periods at its point of application to develop in some of the particles a difference of potential from the point of contact of a particle with an adjacent electrode, and means for separately collecting the separated particles.

21. In an apparatus for separating the particles of a mass, means for feeding comminuted material, means for convectively .delivering charges across the path of mateterial, a separating electrode, means for adjusting the device for desired duration of charging periods at its point of application to said material to develop and maintain a difference of potential from the point of contact of a particle with the separating electrode and from each other, and means for separately collecting the separated particles.

22. In an apparatus for separating the particles of a mass, means for feeding comminuted material, means for convectively delivering charges across the path of the material, means for developing in said particles a dielectric hysteretic impedance by subjecting the particles to the action of a static charge varied in phase, and means for separately collecting the separated particles.

23. In an electrostatic separator, the combination with a grounded separating electrode, a charging electrode adapted to dc.- liver potential to the separating electrode, means for feeding comminuted material between said electrodes,- means adapted to interrupt the delivery of potential to the charging electrode at predetermined intervals, and means for separately collecting the f as separated particles.

24. The combination with the electrodes of an electrostatic separator, of means for charging the electrodes, means for feeding comminuted material to said electrodes, means for interrupting the delivery of potential to said electrodes at predetermined recurring intervals, and means for sepaterminal adapted to discharge toward the' separating electrode, means for feeding comminuted material between said electrodes, and means for separately collecting the separated particles.

26. In an apparatus of the class described, the combination with a separating electrode, of a charging electrode having a series of points adapted to'discharge toward the separating electrode, means for feeding comminuted material between said electrodes, and means for separately collecting the separated particles.

27. The combination with the electrodes of an electrostatic separator and a source of potential, of means for feeding comminuted material to said separator, means for delivering the potential to the particles in a succession of charges localized upon said particles and regulated in duration, and separately collecting the separated particles.

28. The combination with the electrodes of an electrostatic separator and a source of potential, of means for feeding comminuted material to said separator, means for delivering the potential in a succession of charges, each regulated in duration relative to the particles to be separated, and means for separately collecting the separated particles.

29. The combination with a separating electrode, of a charging electrode, means for feeding comminuted material thereto, a division plate, said feeding means and plate being arranged to electrically. shield a portion of the separating electrode from the action of the charging electrode, and means for separately collecting the separated particles.

30. The combination with a separating electrode, of a charging electrode, a grounded feed shelf shield, means for feeding comminuted material between said electrodes, a grounded division plate shield disposed adjacent to the separating electrode, and means for separately collecting the separated particles.

31. The combination with a separating electrode, of a charging electrode, means for producing a convection of the charge from the charging electrode to the separating electrode, means for feeding comminuted material between said electrodes and through thepath of said convective charge, and means for separately collecting the separated particles.

32. The combination with the electrodes of an electrostatic separator, of means for feeding comminuted material thereto, means for charging one of said electrodes, means for reducing and maintaining said charged electrode to substantially zero potential at recurring intervals, and means for separately collecting the separated particles.

33. In an electrostatic separator, a separating electrode, a generator, means for feeding comminuted material thereto, means for convectively charging the particles to be separated in a gap between the separating electrode of the charging means and means intermediate the charging means and generator for delivering to the particles a fraction of the full charge.

34. In an electrostatic separator, a separating electrode, means for feeding comminuted material thereto, an opposite charging electrode, a charged surface for electrically releasing material from said separating electrode, and a regulator in circuit with said surface and having a pointed terminal to effect a continuous flow therethrough'.

35. In an electrostatic separator, a separating electrode, means for feeding comminuted material thereto, an opposite charging electrode, a charged surface for electrlcally releasing material from said separating electrode, a source of supply for said charging electrode, and a regulator disposed in circuit between the source of supply and one electrode and provided with a convectively discharging terminal to maintain a continuous current therethrough.

36. In an electrostatic separator, the combination with a separating electrode and a pointed charging electrode, of means for feeding comminuted material between said electrodes, a source of energy, an interposed interrupter, a connection between the charging electrode and said source to produce different predetermined phases of the charge, means for switching from one to the other of said phases, and means for separately collecting the separated particles.

37. In an electrostatic separator, the combination with a separating electrode and an adjacent charging electrode adapted to deliver a convective charge to the material, of means for feeding material thereto, a source of energy, means for supplying to the particles to be separated an alternation of the polarity of the charge delivered thereto, and means for separately collecting the separated particles. I

38. In an electrostatic separator, the combination with a separating electrode and an adjacent charging electrode, of means for feeding material between said electrodes, a source of energy, an interrupter, conductors for opposite potentials from said source to said interrupter, conductors at the opposite side of said interrupter in alinement with those from the source of energy, a single conductor extending from said opposite conductors to the chargingelectrode, and means for separately collecting the separated particles.

39. In an electrostatic separator, a separating electrode, and opposite charging means for convectively delivering a charge to said electrode and comprising a circuit from a source of potential, said circuit being interrupted by anair gap disposed between adjacent adjustable terminals one of which is adapted to convectively discharge toward the other.

40. In an electrostatic separator, a separating electrode, an opposite charging electrode for convectively delivering a charge to said separating electrode, means for adjusting said charging electrode relative to the separating,electrode,means for passing material to be separated through the path of convection.

41. In an electrostatic separator, a separating traveling electrode, a charging electrode adapted to deliver a convective charge to the material, means for adjusting said charging electrode toward and from the surface of the separating electrode, means for passing material to be separated through the path of convection.

42. In an electrostatic separator, a separating electrode, a charging electrode, an interrupter constructed tot deliver a series of charges to the charging electrode and separated by inactive intervals, and means for varying the duration of saidcharges.

43. In an electrostatic separator, a separating electrode, a charging electrode, an interrupter constructed to deliver a series of charges separated by inactive intervals, and means for predetermining and maintaining an adjustment of the duration of the impulse of said charge.

In testimony whereof we affix our signatures in presence of two witnesses.

Witnesses:

J. WV. KEARBY, DORA MCMAHAN. 

